Wheel suspension

ABSTRACT

A wheel suspension for mounting in a chassis of a working machine, said wheel suspension comprising a drive axle, a wheel and a hub device, said hub device comprising a first hub unit, which is stationary in the axial direction of the wheel suspension and connected to said axle, and a second hub unit, which is connected to the wheel, said second hub unit being adapted to be displaced in the axial direction of the wheel suspension relative to the first hub unit for altering the axial position of the wheel relative to the first hub unit, wherein the hub device also comprises an actuator for controlled actuation of the second hub unit to bring about said displacement. According to the invention, the actuator comprises a hydraulic cylinder ( 51 ), which is arranged inside a protecting and supporting means ( 52 ) for absorbing forces or force components in the radial direction of the hydraulic cylinder, said protecting and supporting means comprising a first supporting sleeve ( 53 ), which is adapted to be connected to the chassis, and a second supporting sleeve ( 54 ), which is directly or indirectly connected to the second hub unit, said supporting sleeves being telescopically arranged within each other for enabling a telescopic movement between the supporting sleeves.

The present invention relates to a wheel suspension for mounting in achassis (1) of a working machine, said wheel suspension comprising adrive axle, a wheel and a hub device, said hub device comprising a firsthub unit, which is stationary in the axial direction of the wheelsuspension and connected to said axle, and a second hub unit, which isconnected to the wheel, said second hub unit being adapted to bedisplaced in the axial direction of the wheel suspension relative to thefirst hub unit for altering the axial position of the wheel relative tothe first hub unit, wherein the hub device also comprises an actuatorfor controlled actuation of the second hub unit to bring about saiddisplacement.

A wheeled working machine, which has an operating arm carrying aload-handling implement at its outer end, is subjected to large loadswhen the implement is working, especially when the operating arm isextended and the implement is at its largest distance from the workingmachine itself and carries large loads, which completely or partiallyclear the ground, or is working in the ground with a great resistancefrom objects or materials in the ground. Accordingly, the workingmachine must have sufficient stability on the ground in order not to tipover in a direction towards the implement, even when the implement picksup loads in the periphery of its working area and especially in thoseparts of the working area which are located at the opposing sides of theworking machine, i.e. transversely to the machine direction or in theextensions of the wheel axles. For some working machines, specialextendable ground supports are required to achieve the necessarystability of the working machine, but this implies that the ground issufficiently firm and does not give way under the ground supports. Inthose cases when no such stability-increasing ground supports are used,or even cannot be used at all, for a given wheel track of the workingmachine, the size of the working area is determined by the weight of theworking machine, in other words, the weight should be sufficient tosupport occurring high loads on the implement also in the periphery ofthe prescribed working area. There are also demands for an increasedworking area from a parked position of the working machines. In order tomeet this demand, which means an increased reach of the implement andthereby an increased load on the working machine, the stability of theworking machine has to be increased correspondingly, something which,accordingly, should be achieved without resorting tostability-increasing ground supports or making the working machine widerpermanently, which would impair the working machine's driveability bothon roads as well as off-road.

All of the problems discussed above are present especially in workingmachines in the form of forest harvesters, which have an extendablecrane arm carrying at its outer end a harvester head, having the task ofgripping around a standing tree, cutting the tree, and thereafterpivoting down the tree, and holding the tree above the ground in orderto carry out delimbing and cutting into logs. Especially when thinningforest, it is desirable to reach further into the thinning stand from aparked position than what has hitherto been possible, in order to, amongother things, be able to increase the distance between the strip roadsalong which the harvester operates. Also during final cutting, however,it is desirable to be able to reduce the number of position changes bybeing capable of increasing the reach of the harvester in each position.

Working machines with or without implement-carrying operating arms,which are used e.g. in forestry, are relatively heavy and thereby causegreat damages to the ground, especially when they are driven on groundwith small carrying capacity for the heavy working machines. The damagesare aggravated due to the fact that all wheels run in one and the sametrack on each side of the working machine. One type of working machinescausing such ground damages is forwarders, which impose a load on aroadway repeatedly for the transport of timber from a forest stand to amotor road. A harvester can also cause ground damages on forestroadways, or on the side of them.

SE 529 713 describes a wheel suspension for a working machine, saidwheel suspension enabling alteration of the track width as required inorder to increase the stability of the working machine and/or todistribute the ground load of the working machine over a larger groundarea. The wheel suspension comprises an axle and a hub device. The hubdevice comprises a first hub unit, which is connected to the axle, and asecond hub unit, which is connected to a wheel of the wheel suspension.The second hub unit can be displaced axially relative to the first hubunit by means of external actuators in the form of hydraulic cylinders,which are arranged between the first hub unit and the second hub unitand extend in parallel with the axle.

One problem with wheel suspensions of the type disclosed in SE 529 713is that the external actuators are at risk of being subjected todamaging shocks and loads. This is particularly a problem in harvesters,forwarders and other types of forest machines, where there is a risk ofrocks, tree parts and other objects being forced up under the forestmachine and hitting the actuators when the forest machine is drivenoff-road.

One solution to this problem is to arrange the actuators internally,i.e. inside the axle of the wheel suspension. This, however, is amechanically complicated and thereby expensive solution, which furtherleads to the problem that the axle occupies a large volume.

Accordingly, there is a need for wheel suspensions of theabove-described type where the actuators are so arranged that they areprotected from damaging load.

The object of the present invention is to produce such a wheelsuspension.

The wheel suspension according to the invention is characterized in thatthe actuator comprises a hydraulic cylinder, which is arranged inside aprotecting and supporting means for absorbing forces or force componentsin the radial direction of the hydraulic cylinder, said protecting andsupporting means comprising a first supporting sleeve, which is adaptedto be connected to the chassis, and a second supporting sleeve, which isdirectly or indirectly connected to the second hub unit, said supportingsleeves being telescopically arranged within each other for enabling atelescopic movement between the supporting sleeves.

In the following, the invention will be described more closely with theaid of a presently preferred embodiment, while referring to the attacheddrawings.

FIG. 1 schematically shows a forest harvester.

FIG. 2 schematically shows, in an exploded view, a wheel axle assemblywith a wheel suspension according to the invention at both of its ends.

FIG. 3 is a perspective view of a first hub unit in the hub device ofthe wheel suspension.

FIG. 4 is an axial sectional view of the hub unit of FIG. 3.

FIG. 5 is an axial sectional view of a second hub unit in the hub deviceof the wheel suspension.

FIG. 6 schematically shows a wheel suspension of FIG. 2 where the secondhub unit is in an extended position.

FIG. 7 schematically shows the wheel suspension of FIG. 6 in a retractedposition.

FIG. 8 schematically shows, in an exploded view, a protecting andsupporting means according to the invention.

FIG. 9 is an axial sectional view of a protecting and supporting meansaccording to the invention in an extended position.

FIG. 10 is an axial sectional view of the protecting and supportingmeans of FIG. 9 in a retracted position.

FIG. 11 is a top view of a wheel axle assembly according to FIG. 2.

FIG. 12 is a perspective view of a first supporting sleeve of aprotecting and supporting means according to the invention.

FIG. 13 is a perspective view of a second supporting sleeve of aprotecting and supporting means according to the invention.

FIG. 1 schematically shows a working machine or contract machine in theform of a forest harvester, which has a chassis 1 and front and rearwheel suspensions for wheels 2. The front wheel suspensions are part ofa bogie axle assembly, and the rear ones are part of a driving wheelaxle assembly 3. A crane arm 4 is pivotally mounted on the chassis 1 andis adapted to carry various types of implements, for example a harvesterhead (not shown), on its outer pivot arm 5.

FIG. 2 shows an exploded view of the rear portion of the chassis 1 andthe wheel axle assembly 3. The chassis comprises a mounting surface 6for the crane arm 4. The wheel axle assembly 3 comprises two opposinghubs 7, which are driven by a transmission system, comprising driveaxles and gears for driving the hubs 7, said transmission system beingarranged in a gear housing 8.

The wheel axle assembly 3 further comprises two opposing hub devices 9of the type described in SE 529 713. Accordingly, each hub device 9comprises a first, inner hub unit 10, which is attached to the hub 7,and a second, outer hub unit 11, which carries the wheels of the wheelsuspension. A combined locking and guiding device carries out the doublefunction of locking the two hub units 10, 11 to each other in thecircumferential direction for their common rotation, and of allowingaxial displacement, by controlled force actuation, of the outer hub unit11 and its wheel 2 relative to the inner wheel unit 10, in order toalter the distance between the wheels 2 of the wheel axle assembly 3 inthe desired way.

Advantageously, said hub units and locking and guiding device can be ofthe known types described in SE 529 713, and which shortly will bedescribed in the following. It is appreciated, however, that other hubunits and locking and guiding devices can be used within the scope ofthe invention.

The inner hub unit 10 comprises a supporting element 12, which has theshape of a hollow cylindrical sleeve (see FIGS. 3 and 4). The supportingelement 12 has a first, inner space 13, having a diameter D₁ which isadapted to a mounting flange 14 of the hub 7, so that the mountingflange 14 can be received in the first space 13 with a good fit, i.e.without detrimental play and without frictional engagement. Furthermore,the supporting element 12 has a second, outer space 15, having adiameter D₂ which is adapted to the cylindrical shape of the hub 7, sothat the hub 7 can be received in the second space 15 with a good fit,i.e. without detrimental play and without frictional engagement, whereinthe axial length of the hub 7 is equal to or slightly smaller than theaxial length of the outer space 15. The two spaces 13, 15 merge intoeach other. It is appreciated that half of the difference between thetwo diameters D₁ and D₂ corresponds to the radial extension of themounting flange 14, plus/minus occurring tolerances. At the transitionbetween the two spaces 13, 15, a radial support surface 16 is formed,against which surface the radial mounting flange 14 is to abut. Aplurality of axial through holes 17 are arranged in the thicker wallportion 18 of the supporting element 12 for passing through bolts (notshown), which are screwed into opposing threaded holes in the mountingflange 14, after the supporting element 12 has been displaced coaxiallyrelative to the hub 7 in order to enclose the same and until the inner,radial support surface 16 meets the mounting flange 14, which serves asa stop. The above-mentioned bolts produce a stable screw joint betweenthe supporting element 12 and the hub 7, so that a stable rotatable unitis formed. The supporting element 12 has an external, rotationallycylindrical surface 19, in which four axial grooves 20 are arranged. Thegrooves 20 are uniformly distributed in the circumferential directionand have their ends located at a distance from the opposing, inner andouter, end surfaces 21, 22 of the supporting element 12. The grooves 20serve as seats for corresponding wedges 23 (see FIGS. 6 and 7),projecting radially outward a predetermined distance from the grooves20. Furthermore, there are radial, diametrically opposing grooves 24 inthe outer end surface 22 of the supporting element 12, said grooves 24allowing passage of lubricant in a direction from outside.

The above-mentioned second, outer hub unit 11 (see FIG. 5) also has theshape of a hollow cylindrical sleeve, and is adapted to enclose theentire first, inner hub unit 10. The expressions “inner” and “outer” areused to indicate the radial positions of the hub units 10, 11 relativeto each other. The outer hub unit 11 has a through-going, cylindrical,unitary space 25 for receiving and enclosing the inner hub unit 10, asis evident from FIGS. 6 and 7. The cylindrical space 25, which thus hasthe same diameter D₃ all the way through, is delimited by a rotationallysymmetrical, internal surface 26 of the wall of the hub unit 11. Theinside diameter D₃ of the hub unit 11, i.e. of the space 25, is slightlylarger than the outside diameter D₄ (see FIG. 4) of the inner hub unit10, so that a small gap of a predetermined size is formed between theircylindrical surfaces 19, 26. The size of the gap should be as small aspossible to reduce angular misalignment between the surfaces 19, 26 andwear of these surfaces. The gap size is suitably between 0.05 and 0.5mm. It is preferably in the lower part of the interval, and mostpreferably it is 0.05-0.1 mm. The outer hub unit 11 has a planar, outerend surface 27, and a planar, inner end surface 28. Both end surfaces27, 28 are provided with axial, threaded holes 29, 30. The outer endsurface 27 is tightly sealed by a cover 31 (see FIGS. 6 and 7), which issecured by screwing to the hub unit 11 by means of bolts in saidthreaded holes 29 thereof, while using a suitable sealing devicetherebetween, e.g. a sealing ring. An axially wide and radially thickmounting flange 32 is formed on the outside of the outer hub unit 11. Asis evident from the following description of the mounting of the hubdevice, the mounting flange 32 is arranged on the other half of the hubunit 11, which is located closest to the wheel of the hub unit 11 and ata distance from the inner end surface 28 of the hub unit 11. Themounting flange 32 is sufficiently wide, i.e. has a sufficient axialextension, in order to leave place for axial, threaded holes 33, 34 inboth directions. The mounting flange 32 exhibits two radial annularsurfaces 35, 36, from which said threaded holes 33, 34 extend. The wheelof the hub unit 11 is secured by screwing to the hub unit 11 by means ofbolts, which are passed through the holes in the rim flange of the wheeland are screwed into the threaded holes 33 of the mounting flange 32.

An annular groove 37 is formed in the internal surface 26 of the wall ofthe hub unit 11, and a plurality of radial apertures 38 extend throughthe wall and open into the groove 37 for entry of lubricant, which fillsthe groove 37 and the gap between the two hub units 10, 11, when theinner hub unit 10 is inserted into the outer hub unit 11.

Furthermore, four axial, parallel guide grooves 39 are formed in theinternal surface 26 of the wall of the hub unit 11, said guide grooves39 extending continuously between the end surfaces 27, 28. The guidegrooves 39 are uniformly distributed in the circumferential directionand are adapted to the dimensions of the projecting or free portions ofthe wedges 23, so that the wedges 23 can move frictionlessly in thegrooves. The wedges 23 and the guide grooves 39 constitute anadvantageous embodiment of said combined locking and guiding device.Accordingly, the wedges 23 and the guide grooves 39 have the doublefunction of locking the two hub units 10, 11 to each other in thecircumferential direction for their common rotation, on the one hand,and of allowing axial displacement, by controlled force actuation, ofthe outer hub unit 11 relative to the inner hub unit 10, on the otherhand, in order to alter the distance between the wheels of the wheelaxle assembly 3, or another axle assembly such as a bogie axle assemblyor non-driven axle assembly with rotatably mounted hubs, in the desiredway.

On its outside, the outer hub unit 11 carries a ball bearing ring 40(see FIGS. 6 and 7), which thus encloses the hub unit 11. The ballbearing ring 40 is located adjacent to the mounting flange 32 andcomprises an outer ring member 41 and an inner ring member 42, which arerotatable relative to each other about an intermediate ball bearing (notshown). The outer ring member 41 is provided with a plurality of axialthrough holes for bolts 43, by means of which the ball bearing ring 40is fixed by screwing to the mounting flange 32 via its outer ring member41, whereas the inner ring member 42, accordingly, has no direct contactof its own with the outer hub unit 11, but only an indirect contact viathe outer ring member 41.

Furthermore, on its outside, the outer hub unit 15 carries a mountingring 44, which thus encloses the hub unit 11. The mounting ring 44 islocated axially outside the ball bearing ring 40 and, with respect toits width, extends all the way to the inner end edge 28 of the outer hubunit 11. The inner ring member 42 of the ball bearing ring 40 isprovided with a plurality of threaded axial holes, whereas the mountingring 44 is provided with a corresponding number of through-going, axialholes for passing through bolts 45, which are secured by screwing to theinner ring member 42 with subsequent fixed attachment of the mountingring 44 to the inner ring member 42.

The hub device further comprises a sealing device 46, which is adaptedto seal the two hub units 10, 11 from the inside. A suitable sealingdevice is a tubular bellows of a suitable resilient material. Thesealing bellows 46 has an outer, annular, radial flange 47 (see FIGS. 6and 7), which is provided with a plurality of screw holes (not shown),and an inner, annular, radial flange 48, which is designed with an axialcollar 49. During the mounting, the sealing bellows 46 is inserted intothe first, inner space 13 of the supporting element 10, whereupon theinner flange 48 and its collar 49 are attached to and fixed against theinner end surface 21 of the inner hub device 10 by means of screw joints50. Thereafter, the outer flange 47 is secured by screwing to the innerend surface 28 of the outer hub unit 11, so that the gap between the twohub units 10, 11, as well as the inner space 13 of the supportingelement 12, are sealed.

The hub device comprises an actuator for controlled axial displacementof the outer hub unit 11 relative to the inner hub unit 10, which isthus axially stationary. In the shown embodiment, the actuator isconstituted of two double-acting hydraulic cylinders 51 (see FIGS. 8, 9and 10) for each wheel and hub device.

According to the invention, each hydraulic cylinder 51 is mounted insidea protecting and supporting means 52 (see FIGS. 2, 6 and 7), which isadapted to absorb radial forces. As used herein, radial forces refer toforces or force components acting in a direction transversely to thelongitudinal direction of the hydraulic cylinder 51. Such forces canarise e.g. as a result of rocks or tree parts being forced up under theworking machine and hitting the wheel axle assembly 3.

Each protecting and supporting means 52 comprises a first, inner,supporting sleeve 53, and a second, outer supporting sleeve 54.

At its outer end, the inner supporting sleeve 53, which is substantiallytubular, comprises an external flange 55 (see FIG. 12), extending in thecircumferential direction around the outer end of the supporting sleeve55. The flange 55 exhibits a plurality of axial openings 56 (see FIGS. 9and 10) being uniformly distributed in the circumferential direction,which openings are adapted to receive bolts 57 for the formation of ascrew joint with the chassis 1. For this purpose, the chassis 1 exhibitsan opening 58 for receiving the inner supporting sleeve 53, on the onehand, and an outwardly facing support surface 59 for interaction withthe flange 55, on the other hand. The support surface 59 exhibitsthreaded holes 60 for receiving the bolts 57. In a mounted state, theinner supporting sleeve 53 is thus recessed into the chassis 1, as isshown in FIG. 11, so that only the flange 55 projects from the supportsurface 59. At its inner end, the supporting sleeve 53 exhibits a tube61, extending transversely to the longitudinal direction of thesupporting sleeve and through the supporting sleeve, which tube at itsmiddle portion has an open portion 62 for receiving an inner attachmentlug 63 of the hydraulic cylinder 51 (see FIGS. 9 and 10). The hydrauliccylinder is locked to the supporting sleeve 53 by passing a pivot pin(not shown) through the tube 61 and the attachment lug 63.

At its outer end, the outer supporting sleeve 55, which is alsosubstantially tubular, comprises projecting, curved wings 64. The wings64 have an inside surface 65, which has a radius of curvaturecorresponding to the radius of curvature of the outside surface 66 ofthe mounting ring 44. The wings 64 exhibit through openings 67 forreceiving bolts 68, and the mounting ring 44 exhibits correspondingthreaded holes 69 for reception of the bolts 68 and the formation of ascrew joint with the supporting sleeve 55, as is shown in FIG. 11. Atits outer end, the supporting sleeve 55 also exhibits an opening 70 forreceiving a locking means in the form of a bolt (not shown), saidopening extending transversely to the longitudinal direction of thesupporting sleeve 55. The mounting ring 44 exhibits a correspondingthreaded hole 71 (see FIG. 2) for the formation of a screw joint withsaid bolt. The hydraulic cylinder 51 comprises an outer attachment lug72 and is locked to the mounting ring 44 by passing said bolt (notshown) through the opening 70 and the attachment lug 72 and threading itinto the threaded hole 71 (see FIGS. 9 and 10).

The inner supporting sleeve 53 has an internal, circularly cylindricallimiting surface 73, having a diameter D₅. The outer supporting sleeve54 has an external, circularly cylindrical limiting surface 74, having adiameter D₆. At its outer end, the inner supporting sleeve 53 exhibitsan opening 75 (see FIG. 12) for receiving the inner end of the outersupporting sleeve 54. The outside diameter D₆ of the outer supportingsleeve 54 is slightly smaller than the inside diameter D₅ of the innersupporting sleeve 53, and the outer supporting sleeve 54 is adapted tomove inside the inner supporting sleeve 53 with a good fit, with thehydraulic cylinder 51 arranged axially inside the supporting sleeves 53,54, as is shown in FIGS. 9 and 10. Accordingly, the supporting sleeves53, 54 are telescopically arranged within each other, and thus enable atelescopic movement between the supporting sleeves 53, 54 in thelongitudinal direction of the hydraulic cylinder 51. At the opening 75,the limiting surface 73 exhibits a recess, into which a cylindricalsliding bushing 76 (see FIGS. 9 and 10) is recessed. Accordingly, thelimiting surface 74 of the outer supporting sleeve 54 forms a supportsurface for interaction with the sliding bushing 76 and/or the limitingsurface 73, which thus forms an internal support surface of the innersupporting sleeve 53. Thereby, the sliding bushing 76 preferably hassuch an extension in the axial direction, that a guiding of the outersupporting sleeve 54 is obtained, so that, in normal conditions, it iscentered inside the inner supporting sleeve 53 and allows radial forcetransmission between the support surfaces 73 and 74 only to a limitedextent.

For axial displacement of the outer hub unit 11 relative to the innerhub unit 10, the wheel axle assembly 3 comprises two hydraulic cylinders51 on each side, each being arranged inside protecting and supportingmeans 52 in the above-described way. Each hydraulic cylinder 51 is, withits piston rod 77, connected to the chassis 1 via the inner supportingsleeve 53 and, with its piston cylinder 78, to the mounting ring 44 ofthe outer hub unit 11. When connecting the hydraulic cylinders 51 forextending their piston rods 77, the pressure force will be transferredto the outer hub unit 11 via the attachment lugs 72, the mounting ring44, the ball bearing ring 40, and the mounting flange 32 of the outerhub unit 11. Since the outer hub unit 11 is not fixed to the inner hubunit 10 in the axial direction, but only in the circumferentialdirection, the outer hub unit 11, together with its wheel, the rim ofwhich (not shown) is fixedly mounted to the outer hub unit 11, will bedisplaced in a direction outward relative to the inner hub unit 10. Theoutward displacement can take place until the inner end surfaces 21, 28of the two hub units 10, 11 become flush with each other, as is shown inFIG. 6. In order to increase the track width or wheel track of the wheelaxle assembly 3 even more, the outer hub unit with wheel of the second,opposing hub device, is displaced in a corresponding way.

Accordingly, the inner supporting sleeve 53 is rigidly connected to thechassis 1 and the outer supporting sleeve 54 is rigidly connected to themounting ring 44 of the outer hub unit 11. All external forces or forcecomponents acting on the supporting sleeves 53 and 54 will thus betransferred to the chassis 1 and the outer hub unit 11, respectively,without imposing any load on the hydraulic cylinder 51 arranged insidethe supporting sleeves 53, 54. Furthermore, the design of the protectingand supporting means 52 enables external forces or force components tobe distributed between the supporting sleeves 53, 54, since the designallows radial force transmission between the supporting sleeves 53, 54,either via the sliding bushing 76 or directly via the support surfaces73 and 74. Thus, also in such a situation, no load is imposed on thehydraulic cylinder 51 arranged inside the supporting sleeves 53, 54.

Accordingly, according to the invention, the inner supporting sleeve 53is directly or indirectly connected to the chassis 1, so that it isstationary in the axial direction of the wheel suspension.

The forest harvester is preferably provided with a lifting device, whichis extendably or lowerably mounted in the chassis 1 in the vicinity ofthe drive axle assembly or another axle assembly with adjustable wheelsuspensions, in order to be brought to bear against the ground orsupport to thereby lift the forest harvester a sufficient distance, sothat the wheels of the drive axle assembly clear the ground or thesupport, whereupon one or both wheels can be displaced axially byconnecting the hydraulic cylinders 51. The wheels can also be displacedaxially during movement of the forest harvester by simultaneousconnection of the hydraulic cylinders 51.

In the foregoing, the invention has been described starting from aspecific embodiment. It is appreciated, however, that other embodimentsor variants are conceivable within the scope of the invention. Forinstance, a sealing, for example in the form of an O-ring 79 (see FIGS.9 and 10), can advantageously be arranged at the opening 75 to preventcontaminants from penetrating in between the support surfaces 73 and 74.

It is also appreciated that the protecting and supporting means 52according to the invention enables other advantageous designs. Adistance sensor, for example a laser sensor 80 (see FIG. 11), can e.g.be placed protected inside one of the supporting sleeves in order tomonitor and control the extension movement of the outer hub unit 11. Forinstance, a laser sensor 80 (see FIGS. 9 and 11) can be fixed inside theinner supporting sleeve 53, at the inner end of the supporting sleeve53, in order to measure the distance to the inner cylinder surface 81 ofthe hydraulic cylinder 51 or to the inner end surface 82 (see FIG. 9) ofthe outer supporting sleeve 54. It is appreciated that the distancesensor alternatively can be placed inside the outer supporting sleeve 11in order to monitor and control the extension movement by measuring thedistance to the inner supporting sleeve 10 directly or indirectly.

The invention can be applied to any working machine, where increasedstability and/or increased track width according to the requirements isdesired, such as forwarders, but in addition to harvesters as describedabove, also to regular tractors for e.g. agriculture. The invention canalso be applied to machines being pulled by a vehicle, e.g. anagricultural tractor, and which are usually single axled, i.e. have onlyone axle assembly, where it is desired that the machine being pulled hasa different, e.g. larger, track width than the one of the tractor, inorder to thus spare the ground.

It is further appreciated that the invention can be applied to workingmachines which are at least intermittently track-bound, e.g. to workingmachines for railroad maintenance, which working machines, on the onehand, have conventional, air-filled wheels for transporting the workingmachine on the road and, on the other hand, extendable railroad wheels,which are suspended according to the invention for quick and easyadjustment of the correct wheel track.

1-9. (canceled)
 10. A wheel suspension for mounting in a chassis of aworking machine, said wheel suspension comprising: a drive axle; awheel; and a hub device, said hub device comprising a first hub unit,which is stationary in the axial direction of the wheel suspension andconnected to said axle, and a second hub unit, which is connected to awheel, said second hub unit being adapted to be displaced in the axialdirection of the wheel suspension relative to the first hub unit foraltering the axial position of the wheel relative to the first hub unit,wherein the hub device also comprises an actuator for controlledactuation of the second hub unit to bring about said displacement,wherein the actuator comprises a hydraulic cylinder, which is arrangedinside a protecting and supporting means for absorbing forces or forcecomponents in the radial direction of the hydraulic cylinder, saidprotecting and supporting means comprising a first supporting sleeve,which is adapted to be connected to the chassis, and a second supportingsleeve, which is directly or indirectly connected to the second hubunit, said supporting sleeves being telescopically arranged within eachother for enabling a telescopic movement between the supporting sleeves.11. The wheel suspension according to claim 10, wherein the piston endof the hydraulic cylinder is connected to the first supporting sleeve,and in that the cylinder end of the hydraulic cylinder is connected tothe second supporting sleeve.
 12. The wheel suspension according toclaim 10, wherein the first supporting sleeve comprises an internalcylindrical support surface, which comprises a recess into which asliding bushing is recessed, and in that the second supporting sleevecomprises an external cylindrical support surface, which is adapted tointeract with the sliding bushing during said telescopic movement. 13.The wheel suspension according to claim 12, wherein the sliding bushingis arranged at an end of the first supporting sleeve exhibiting anopening for receiving the second supporting sleeve.
 14. The wheelsuspension according to claim 12, wherein the tolerances of the internalsupport surface and the external support surface allow a radial forcetransmission to take place between the supporting sleeves.
 15. The wheelsuspension according to claim 13, wherein the protecting and supportingmeans comprises a sealing, which is arranged between the supportingsleeves at the opening for preventing contaminants from penetrating inbetween the support surfaces.
 16. The wheel suspension according toclaim 10, wherein the protecting and supporting means comprises adistance sensor, which is arranged inside the first supporting sleeve orthe second supporting sleeve for measuring the extension of the outerhub unit.
 17. A working machine having front and rear axle assemblies,which are provided with wheel suspensions, wherein at least one of thewheel suspensions comprising: a drive axle; a wheel; and a hub device,said hub device comprising a first hub unit, which is stationary in theaxial direction of the wheel suspension and connected to said axle, anda second hub unit, which is connected to a wheel, said second hub unitbeing adapted to be displaced in the axial direction of the wheelsuspension relative to the first hub unit for altering the axialposition of the wheel relative to the first hub unit, wherein the hubdevice also comprises an actuator for controlled actuation of the secondhub unit to bring about said displacement, wherein the actuatorcomprises a hydraulic cylinder, which is arranged inside a protectingand supporting means for absorbing forces or force components in theradial direction of the hydraulic cylinder, said protecting andsupporting means comprising a first supporting sleeve, which is adaptedto be connected to the chassis, and a second supporting sleeve, which isdirectly or indirectly connected to the second hub unit, said supportingsleeves being telescopically arranged within each other for enabling atelescopic movement between the supporting sleeves.
 18. The workingmachine according to claim 17, wherein both axle assemblies are providedwith said wheel suspensions and the working machine is at leastintermittently track-bound.